Plants And Biodiversity PPQs

Question 1

During the light independent reaction of photosynthesis, carbon dioxide is converted into organic substances. Describe how. (6)

Answer 1

Carbon dioxide combines with Ribulose Biphosphate

Produces two GP (glycerate phosphate)

GP reduced to TP (triose phosphate)

Using reduced NADP

Using energy from ATP

Triose Phosphate converted to glucose

Question 2

Suggest how the ecologists decided to take the samples of captured insects on a number of sites on an island (2)

Answer 2

Draw grid over map of area

Select coordinates using random generator

Question 3

Give two assumptions made when using the mark release recapture method. (2)

Answer 3

No immigration or emigration
No losses to predation
Marking doesn’t affect survival
Birth rate and death rate equal

Question 4

Suggests the advantage of using fluorescent powder in the mark release recapture experiment (2)

Answer 4

Fluorescent powder only glows brightly in UV light so doesn’t make insect more visible

So it doesn’t increase predation on insect

Question 5

Equation for mark release recapture

Answer 5

Estimated population size = total number individuals in 1st sample x total number individuals in second sample / total number marked individuals recaptured

Question 6

Suggest one way the method used by the ecologists may have caused an increase in their estimates of the size of insect population (2)

Answer 6

They removed large numbers of insects from the same AREA

Which affected the ratio of marked to unmarked

Question 7

Calculate the number of insects on the island one day after release of the marked insects

Answer 7

WHAT IS THE ANSWER
HOW THE DUXK DID THEY GET
10 130

Question 8

What does genetic diversity mean on a genetic level rather than population level?

Answer 8

Population - number of different alleles of genes in a population

Genetic diversity when comparing same genes between animals - number of different alleles of each gene

Question 9

What is the difference between species richness and an index of diversity? (2)

Answer 9

Species richness only measures the number of different species, not the number of individuals

Question 10

Suggest why there was variation in the height of traps in the trees if they were measuring species of butterfly in the leaves versus understorey. (1)

Answer 10

Trees vary in height

Question 11

Explain what the results of the statistical test (p values) of the butterfly distribution shows.(3)

Answer 11

Greater than 5% probability of difference in distribution of Z. Itys being due to chance

For all other species the difference in distribution is unlikely to be due to chance

Because the p value is < 0.001 which is highly significant/ much less than 5%

Question 12

Suggestion how this student would obtain data to give a more precise index of diversity of this habitat (2)

Answer 12

Take more samples and find the mean

Using random sampling with a random generator

Question 13

Suggest one consideration the scientist had to take into account to make sure the message allowed them to identify accurately the species to which each bee belonged (1)

Answer 13

Method must allow close examination and use key (field guide) to identify species

Question 14

Bee question

Suggest and explain two ways in which the scientist could’ve improved the messages for data collection in this investigation (2)

Answer 14

Collect bee samples at more times of the year - so more plots on the graph

Collect sample of bees from more sites - to improve accuracy

Question 15

Do these days to show that there were any significant changes in the grass and communities on these islands?(3)

Answer 15

Because greater than 5% probability of getting that species diversity change on Islay by chance.

So change in diversity in Islay not significant

Less than 0.001 probability the increase in species richness on Islay and Colonsay is due to chance so difference is significant. Less than 0.001 probability decrease in Harris is due to chance so decrease is also significant.

Question 16

Why was the index of diversity of insects higher in the hedge that in the barley field (3)

Answer 16

More plant species/ larger diversity of plants
More habitats/niches
More food resources

Question 17

Explain the purpose of a control

Answer 17

Ensures results aren’t due to another factor

Question 18

Describe how to determine the main percentage cover for beach grass on a sand dune (3)

XX

Answer 18

Random sampling with random generator

Use large sample of quadrats (20+)

Divide total % by number of quadrats

Question 19

Succession marking points (4)

Answer 19

Pioneer species (named species)

Changes conditions

making them less hostile for (named species)

(Named species) represents climax community

Question 20

Using evidence from figure 2 what can you conclude about the net primary productivity in the sand dunes that older than 1000 years (2)

Answer 20

NPP constant because GPP and R are constant

Question 21

Give two differences in the variation in body length of male and female thorny lizards (2)

Answer 21

Female lizards tend to have longer body length

Female lizards have more variation in body length

Question 22

Give one limitation of using a transect to collect this data (1)

Answer 22

Transect line may not go through representative area/may avoid certain areas

Question 23

What information does the bar representing standard deviation give? (1)

Answer 23

Shows the spread of data

Around the mean (say what the mean is eg. Around the mean height of plants)

Question 24

Describe what the results show about the variation of the height of plants in relation to altitude. (2)

Answer 24

Plants are shorter at higher altitudes

Higher the altitude the lower the standard deviation

Question 25

Why does a small standard deviation occur?

Answer 25

Because an abiotic factors limited extreme values

Question 26

What does a low standard deviation means in terms of reliability

Answer 26

Smaller range | Results more reliable

Question 27

Describe how you would collect a random sample of each population of dog whelk (3)

Answer 27

``` Use random generator Large sample (use 20+ quadrats) Identify and COLLECT dog whelk species in the quadrat ```

Question 28

What did the standard deviations tell you about the two populations of dogwhelks?

Answer 28

(Population A has larger standard deviation) so greater spread around the mean So greater variation in population A

Question 29

Suggest how the effect of wave action on the two populations of dog whelks could result in differences between The mean L/A ratios The standard deviations (4)

Answer 29

B has a smaller L/A ratio than A so it has a relatively larger foot So can grip better (because it lives in place where there is large wave action) B has a smaller standard deviation than A because wave action limits extreme values So greater age range on the shore (because extreme values can live so larger range of ages?)

Question 30

Niche

Answer 30

No two species of THE SAME GENUS can occupy the same niche

Question 31

Explain how the results shown in the graph relate to the distribution of these to see which on the seashore (3)

Answer 31

Spiralis retains more water Because better adapted to drier conditions (Spiralis is on the upper shore whereas serratus on the lower shore because same genus so) to avoid competition of light/abiotic factor

Question 32

The wolf numbers are given per unit area. Explain why.(2)

Answer 32

To allow for comparison Because different sized areas covered

Question 33

When something is PER something think ...

Answer 33

You are controlling the variable that comes after per

Question 34

Prey-predator relationships think about...

Answer 34

Energy transfers

Question 35

Suggest why pre-index gives a better idea of food available(2)

Answer 35

Takes into account if the wolf doesn’t eat all of the animal Takes into account if (individual) prey have different proportions of edible/inedible parts

Question 36

What does the graph suggest about the factors that determine the wolf numbers in North America? Explain your answer (2)

Answer 36

As prey increases, wolf numbers increase But large range so other factors must be involved

Question 37

Explain what a carbon dioxide uptake is a measure of net productivity (1)

Answer 37

NPP = GPP - R | Shows productivity minus respiration

Question 38

And explain how the shade plant is better adapted in the Sun plant to grow in at low light intensities (2)

Answer 38

Shade plant has lower rate of respiration Because less carbon dioxide released at 0 light intensity So it has greater productivity and more sugars available

Question 39

Describe how you would investigate the distribution of Marholm grass from one side of the dune to the other (3)

Answer 39

Lay a transact Place quadrants at regular intervals along the line Count plants in quadrats

Question 40

Use your knowledge of succession to explain how planting marram grass is useful in helping sand dune ecosystems recover from damage (2)

Answer 40

Stabilises sand Marram improves soil making conditions less hostile

Question 41

The species that are present change during succession. Explain why (2)

Answer 41

Pioneer species change environment So less hostile (So new species that colonise) are better competitors )and outcompete the pioneer species)

Question 42

The pine trees have leaves all year. Explain how this results in a low species diversity of plants in the forest.(1)

Answer 42

Only plants that can PHOTOSYNTHESISE with less light remain

Question 43

What is an increase in the index of diversity suggest about the organisms (2)

Answer 43

Increases in number of different species Increase in numbers (of individuals) of some species

Question 44

Describe the features of a succession that would bring about an increase in the index of diversity (3)

Answer 44

Initial environment hostel/few organisms adapted Adapted organisms change environment More habitats/more niches Allowing other organisms to become established

Question 45

Explain how a change in species composition occurs in a succession (2)

Answer 45

Pioneer species change habitat/environment Another species can colonise These new species are better competitors (outcompete the old species)

Question 46

What makes a climax community the most stable? (2)

Answer 46

More species present More complex food webs Change in one species will have little effect on others As alternative food sources

Question 47

Suggest how sunken stomata give an advantage to xerophytes (3)

Answer 47

Pocket of saturated air trapped near stomatal pore Reduces water potential gradient Reduce TRANSPIRATION

Question 48

Why is it more appropriate to use a transect rather than quadrats in this investigation (1)

Answer 48

Sereines of changes over a distance | Ensures sampling of each community

Question 49

Explain how succession resulted in the formation of the climax community (4)

Answer 49

Pioneer species colonise land Changing the environment (give example) Enables change in species (that can grow - basically different species able to colonise) Conditions change father to favour (growth of) trees

Question 50

Explain why the buggy is described as a climax community (1)

Answer 50

No further succession | Stable community

Question 51

Suggest for trees are unable to survive in waterlogged soils which lack oxygen (2)

Answer 51

Roots cannot aerobically respire | So active transport of minerals stops

Question 52

The water and soil in Sphagnum bogs are usually acidic. Suggest why Sphagnum is not fully decomposed after it dies. (3)

Answer 52

Action of decomposers is inhibited Because acid conditions inhibit/denature enzymes Because the H+ ions affect the active site of the enzymes

Question 53

Explain why the soil nitric concentration is as shown in the graph (2)

Answer 53

Increasing dead organisms Nitrifying bacteria convert ammonia to nitrates

Question 54

The pioneer plant had seeds that germinate better when the temperature fluctuates. Explain the advantage of this to these pioneer plants. XXXX

Answer 54

Bare Soil temperatures fluctuate More bare soil in early succession

Question 55

Explain the advantage to plant the colonises after 50 years, of having a high rate of photosynthesis at low light intensities (1)

Answer 55

Plant will survive in shade if overshadowed by taller plants

Question 56

Conservation of grassland habitats involves management of succession. Use the data on the graph to explain why. (2)

Answer 56

Small annual plants will be outcompeted by woody plants So woody plants must be removed/grazed

Question 57

Describe how the numbers of aerobic bacteria after six months change with depth. (2)

Answer 57

Decrease then remain constant | From 200cm

Question 58

Explain the difference in the numbers of aerobic bacteria at a depth of 300 cm between one and six months. (2)

Answer 58

Oxygen decreases because soil becomes more compact it Decrease in oxygen leads to fewer aerobic bacteria surviving

Question 59

Explain how the changes in bacterial numbers which take place at 150 cm illustrate the process of succession. (3) XXX

Answer 59

Oxygen decreases by aerobic bacteria So anaerobic bacteria replace (outcompete) aerobic bacteria As aerobic bacteria are no longer able to survive in these (low oxygen) conditions Remove competition ???

Question 60

From what depths in the soil store would you expect the soil samples to have been taken? Use info from table one to explain your answer (2) ???? Wahtttt

Answer 60

Near the surface | Table shows decrease with time at greater depths

Question 61

How do you expect dehydrogenase activity to vary with depth after six months? Use information from table 1 to explain your answer.

Answer 61

Dehydrogenase activity decreases Because fewer aerobic bacteria as depth increases So (less aerobic respiration because) oxygen concentration decreases

Question 62

What does Erebus tell you about the difference between the main dehydrogenase activity at six months and three years? Explain your answer in terms of probability and chance. (3)

Answer 62

Results are significant Because error bars do not overlap Greater than 95% probability results are NOT DUE to chance (or less that 5% probability results are DUE to chance)

Question 63

Explain how you would use table to to predict likely number of aerobic bacteria and 1 g of the soil sample. (3)

Answer 63

Plot a graph Draw a line of best fit Read off appropriate value (aka extrapolate)